1. Field of the Invention
This invention relates to textured and painted slats for both vertical and horizontal window or door blinds, and, more particularly, to a method for preferentially coating textured surfaces of such slats with paint, so that the peaks or ridges are coated more heavily than surrounding surfaces.
2. Background Information
A highly desirable feature of horizontal and vertical blind slats is a well-defined, highly-visible surface texture, which differentiates the slats from the plain, sterile appearance generally associated with plastic blind slats. A conventional method for obtaining such a surface texture is through the use of a fabric material. A narrow strip of fabric may itself be used as a vertical blind slat, with a metal weight sewn into the strip at its bottom end being used to provide a measure of stability for the slat, which would otherwise be much too light in weight to hang straight or to resist excessive movement in air currents. Altemately, a fabric strip may be applied to one or both sides of a thermoplastic slat material, such as an extruded PVC strip, which provides weight and rigidity. The fabric may present an ordinary textile appearance, or its appearance may be enhanced by weaving in fibers of larger diameter and differing colors. One problem associated with the use of fabric in these ways is a high maintenance requirement caused by dust and dirt lodging in the fibers of the porous fabric material, resulting in blinds which are particularly difficult to clean. This problem can also result in a shortened practical life of the horizontal or vertical blinds, which eventually become impossible to clean effectively.
What is needed is a way to produce a visual effect of a well-defined, highly-visible surface texture on the surface of an extruded plastic strip, without a necessity for using a porous fabric overlay.
Translucence is an optical property which is highly desirable in window coverings to afford admission of sunlight into a room during the day without compromising privacy at night. Popular examples of translucent window coverings are found in shades using translucent fabric materials, which may be rolled up on a single roll at the top of a window, or which may be raised into a pleated or accordion fold as Roman shades. While such shades can be lowered to cover a window or raised to reveal a clear view, they are limited to presenting a rectangular translucent area; they cannot be partially opened to reveal slots through which the outside world may be viewed. On the other hand, horizontal or vertical blinds are variable louvered structures, which may be fully closed, fully open and drawn back, or partly open to present a number of slots through which the outside world may be viewed.
However, blinds are not available with translucent slats. Part of the reason for this is caused by the fact that blinds are typically exposed to very harsh ultraviolet energy, both from exterior sunlight and from interior fluorescent lighting. Slats for horizontal and vertical blinds are often composed of thermoplastic materials, such as PVC (polyvinyl chloride), which are available in clear or translucent forms. However, such materials are subject to severe discoloration when they are exposed to ultraviolet light, unless they include UV stabilizers. These UV stabilizers additionally turn a transparent material into a translucent material. However, when otherwise transparent PVC is loaded with sufficient UV stabilizers to achieve an adequate lifetime in use as a blind slat, and when such material is formed into a slat having a thickness sufficient to provide the rigidity needed in a blind application, the resulting slat is essentially opaque, lacking an ability to provide indoor lighting by transmitting outdoor light during daytime.
Therefore, what is needed is a slat for vertical or horizontal blinds having a combination of sufficient thickness for rigidity, sufficient UV stabilizers to prevent discoloration, optical translucence, and a well defined surface texture, which is clearly visible both under conditions of backlighting (as viewed from inside during the day) and front lighting (as viewed from inside during the night).